IGCSE Biology glossary
Excretion
Biology editorial review is supported by the named review panel. Reviewer participation may vary by guide. Checked against Cambridge IGCSE Biology 0610 (2026–2028); last reviewed August 2026.
Definition
The removal from organisms of the waste products of metabolism (chemical reactions in cells including respiration), toxic materials, and substances in excess of requirements.
What to include in an exam answer
the key terms are 'waste products of metabolism' (or 'chemical reactions in cells') and 'toxic' and 'in excess of requirements'. The mark students drop most is confusing this with egestion: examiners want you to know excreted substances were made inside cells, not just passed through the gut. Carbon dioxide from respiration and urea from the liver are the classic examples to name.
Example in context
Asked to define excretion: 'Excretion is the removal of the toxic waste products of metabolism, such as carbon dioxide and urea, and substances in excess of requirements, from the body.'
Related syllabus topic
Excretion in humans